neural correlates of lidocaine analgesia

Conditions: Anesthesia; Pain

Summary: the purpose of this study is to characterize the effects of intravenous lidocaine on pain processing and cognitive function. functional magnetic resonance imaging will be used to identify the neural correlates of these phenomena. the study will consist of 1 visit and involves no long-term follow up.

this is an observational cohort study of volunteer subjects, which will employ neuroimaging and behavioral measures to characterize the effects of intravenous lidocaine on pain processing and cognitive function. a steady-state effect-site concentration of lidocaine will be achieved, and a short battery of cognitive behavioral tasks will be employed. at the dose target, pain task functional mri and resting-state connectivity will be determined. this work will use a systems neuroscience approach to fill an important knowledge gap about the central effects of intravenous lidocaine, a commonly-used opioid alternative analgesic agent. aim1: determine cognitive behavioral effects of a steady-state dose of iv lidocaine using a short battery of tasks. the investigators hypothesize that the administration of lidocaine will correlate to decreased pain ratings, slowed psychomotor response, and decreased memory encoding. aim2: determine the neural effects of a steady-state dose of iv lidocaine in response to acute pain, and on resting connectivity. the investigators hypothesize that pain task-related activation will decrease in the insula and anterior cingulate, corresponding to decreased ratings of pain intensity and unpleasantness. additionally, the investigators expect widespread decreases in long-range functional connectivity between brain areas know to be involved in these two areas and other known to be involved in pain processing.

Eligibility criteria:
inclusion criteria: * adults aged 18 to 70 * be of normal body-weight * be generally healthy * have none of the specific exclusion criteria * have a valid email address and phone number throughout the study exclusion criteria: * pregnancy * body mass index \> 40 * having moderate to severe sleep apnea * having chronic pain requiring the regular use of pain medicine 3 or more times per week * having neurologic or psychiatric disease, including benign tremor, anxiety, and depression * having a history of seizures * having history of cardiac rhythm disturbance (such as heart block, or atrial fibrillation) * being severely claustrophobic * having metal implants or non-removable metal piercings * having metal-containing tattoos, particularly on the face * having a history of adverse reaction to lidocaine * are regularly taking: antiepileptics, antidepressants, anti-psychotics, anti-anxiety medication, stimulants, sleep-aids, or pain medication * are taking prescribed medications for psychiatric or neurological conditions * having hypersensitivity to lidocaine or to any other local anesthetics of the amide type * having wolff-parkinson-white syndrome * having known renal or hepatic dysfunction * having glucose-6-phosphate dehydrogenase deficiency or history of methemoglobinemia

Keywords: lidocaine functional mri electric nerve stimulation functional connectivity